Air compressor tripping circuit breaker


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Old 04-09-17, 05:25 PM
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Air compressor tripping circuit breaker

Which is bad, motor or pump? How can I tell?

I have been using a second-hand compressor on 15A 120V for more than a year. 25 gallon 1 HP. Recently, it started to trip circuit breaker. I installed a dedicated 12-3 with 20A circuit breaker. It still trips the CB.

I removed the belt and ran the motor. No problem. But when the belt was in, CB got tripped. I moved the pump wheel manually. I heard scraping sound with intermittent popping sound. Checked oil level. Removed pump head and verified oily film on cylinder wall.

How do you tell which is bad? I suppose the pistons have a wear ring. How do I check it? Worth repairing? Or buy a new pump?
Thank you.
 
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Old 04-09-17, 05:49 PM
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Does it pop the breaker when it is just starting up or after it has run for a while? Does it pop it more often the longer you use it?
 
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Old 04-09-17, 08:39 PM
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With 14-3 and 15A, as soon as it started, it popped the breaker. With 12-3 and 20A, it runs 5 sec and pops the breaker. Since it pops every time, I cannot use the compressor.
 

Last edited by paker; 04-09-17 at 09:04 PM.
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Old 04-10-17, 08:45 PM
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Checked START and RUN capacitors. START is within range, but 40 uF RUN is measured as zero. I just ordered a new one online. Will see in a few days.
 
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Old 04-10-17, 09:27 PM
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Measured as zero would mean a dead short and that could cause your problem.
 
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Old 04-10-17, 09:31 PM
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Note: It isn't 12-3 if it is 120 volts. It is 12-2, Black, white, ground. !2-3 is black, red, white, ground.
 
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Old 04-11-17, 07:41 PM
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Thank you for confirming that a shorted capacitor is the culprit.

I got mixed up between 12-2 and 12-3. Thank you for the correction.
 
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Old 04-13-17, 07:46 PM
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I put a new run capacitor. The air compressor is running well without tripping the breaker. T hank you.
 
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Old 04-13-17, 08:10 PM
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Thanks for letting us know you got it.
 
 

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